1. Field of the Invention
The present invention relates to a cage to protect a transceiver module from electromagnetic interference (EMI) while accommodating the transceiver module for transmitting and receiving electrical signals or optical signals.
As the transceiver module, for example, SFP (Small Form Factor Pluggable) optical communication interface modules are given.
2. Description of the Related Art
In an optical communication system, a transceiver cage is installed, for example, at a position corresponding to a connector on a circuit board so as to accommodate a light transceiver module touchable with the connector. The light transceiver module has a facility to convert into optical signals from electrical signals or electric signals from an optical signals. In this case, it is necessary for electromagnetic interference (EMI) to be removed. The transceiver cage which is made of a metal plate functions as an electromagnetic interference (EMI) screening. Furthermore, it comprises function of protecting from damage and dust as well as the function of the electromagnetic interference (EMI) screening.
A prior-art example of such a transceiver cage is explained based on FIG. 12 and FIG. 13. FIG. 12 is a perspective view of a conventional transceiver cage watched from the base side. FIG. 13 is a drawing of resilience pieces 58a, 58b shown in FIG. 12 watched from a bottom side.
The conventional transceiver cage shown in FIGS. 12 and 13 comprises a housing 51 and two resilience pieces 58a, 58b. 
The housing 51 includes a top plate 52 and a bottom plate 53 and a back plate 54 and the first side plate 55 and the second side plate 56. And, an opening 57 for accommodation a transceiver module is formed in the front.
The resilience pieces 58a, 58b, protrude toward the front side by a predetermined space in the housing 51 so that the transceiver module accommodated in the housing 51 may be pushed away to the opening 57 side.
A latch member 59 which engages with the transceiver module is provided for the housing 51 so as to hold the transceiver module accommodated in the housing 51 against a force of the resilience pieces 58a, 58b. 
Engaging and releasing between the transceiver module and the latch member 59 of the housing 51 enable the transceiver module to attach to and detach from the transceiver cage.
Each upper part of the first side plate 55 and the second side plate 56 is extend from the end on the back plate side so as to make the upper extension part. Each of the resilience pieces 58a, 58b is formed by curving the upper extension part into the housing 51. As shown in FIG. 13, each of the resilience pieces 58a, 58b is consisted of a first bend section 60, a second bend section 61 and a planar section 62. The first bend section 60 constitutes an end portion on the back plate side. The second bend section 61 constitutes an end portion of the protrusion side. The planar section 62 is provided between the first bend section 60 and the second bend section 61. Each of the resilience pieces 58a, 58b protrudes from the back plate 54 side towards the opening 57 in the front of the housing 51.
The first bend sections 60 are joint portions for respectively connecting the resilience pieces 58a, 58b to the first and second side plates 55, 56. The second bend section 61 is a part for touching the transceiver module firstly, which prevent a back of the transceiver module from being scraped and injured by tips of the resilience pieces 58a, 58b. When the transceiver module is accommodated, the resilience pieces 58a, 58b press the back of the transceiver module. When engagement between the transceiver module and the housing 51 is released, the resilience pieces 58a, 58b push out and eject the transceiver module by their elasticity.
However, according to the conventional transceiver cage, there was a problem that the first bend section 60 of each resilience piece was easy to cause plastic deformation by frequent repetition of putting the transceiver module in and out the transceiver cage. When the first bend section 60 causes plastic deformation, the resilience efficiency of the resilience piece falls down then the ejection function of the transceiver module falls down. The present invention was done in view of the problem and it is the purpose to provide a transceiver cage of which a life time becomes long by improving a durability of a resilience piece.